The present invention is directed to a dental instrument for treating teeth with laser beams that are directed from a transmission element arranged in a head part of a dental handpiece.
Dental instruments which utilize laser beams are disclosed by EP-A-375,578 and by German 3,800,555.
A problem with instruments that have an optical light exit window is that deposits, whether in the form of spray water, fog or ablation products from the preparation location, can form on the last optical boundary surface of the beam optics during the treatment. These deposits will deteriorate the light transmission capabilities of the optics. Thus, the efficiency as a consequence of the dampening effects of the deposits will be decreased and, in some instances, the deposits are even capable of damaging the optics.
In an arrangement disclosed by German Gebrauchsmuster 92,04,412, an attempt to overcome this problem has spray nozzles located in the proximity of the beam discharge for spraying cooling or cleaning liquid into the region immediately adjacent to the beam discharge in order, thus, to effect a cleaning of the discharge, on the one hand, and to effect a cooling of the material charged by the laser emission, on the other hand. The cleaning of the optical boundary surfaces of a beam optics with water is risky for two reasons. First, the water itself is always a carrier of contaminants and always contains superfine dirt or other particles that can precipitate at the boundary surface of the beam optics. A second problem is an undesirable dampening effect that will deteriorate the efficiency of the light transmission capabilities occurs when water strikes optical boundary surfaces from which a laser beam emerges.